The spine is divided into four regions comprising the cervical, thoracic, lumbar, and sacrococcygeal regions. The cervical region includes the top seven vertebral members identified as C1-C7. The thoracic region includes the next twelve vertebral members identified as Th1-Th12. The lumbar region includes five vertebral members L1-L5. The sacrococcygeal region includes nine fused vertebral members that form the sacrum and the coccyx. The vertebral members of the spine are aligned in a curved configuration that includes a cervical curve, thoracic curve, and lumbosacral curve. Intervertebral discs are positioned between the vertebral members and permit flexion, extension, lateral bending, and rotation.
As is known, various conditions and ailments may lead to damage of the spine, intervertebral discs and/or the vertebral members. The damage may result from a variety of causes including, but not limited to, events such as trauma, a degenerative condition, a tumor, or infection. Damage to the intervertebral discs and vertebral members can lead to pain, neurological deficit, and/or loss of motion.
Damage to a vertebral bone or a vertebral member may require removal of the vertebral body. This operation is known as a corpectomy. Following corpectomy, the resultant gap is generally filled by a weight bearing support, such as an autologous bone graft, or other devices known as a vertebral body replacement (VBR) cage. This helps to restore and maintain the proper spacing between the adjacent bones, and often provides a space for placement of graft material to span the adjacent bones in order to allow bone fusion to take place. Such replacement implants may be inserted to replace the damaged vertebral bodies and/or discs. The implants are intended to provide structure support and thus reduce or eliminate the pain and maintain neurological function. However, the resultant bone fusion may inevitably limit the range of motion between the indexed vertebral bodies. Although the current structural grafts and vertebral body replacement devices provide good weight support and induce arthrodesis, none of them can allow physiological movement between each of the vertebral segments involved. Therefore, a need remains for an implant that will overcome these shortfalls.